Whiterabbit's 2015 Mercedes GLA 45 AMG

[Ge0]

First of all nice work. Mi gusta!!!!

Now for my first round of questions:

1.) You built your own miniDSP to save a few bucks. Damn that's dedication to taking the cheap way out . Have any more pictures of that? You fabricated your own aluminum box? I would have thought the cheap way out would be to order a cheap ABS plastic project box from Digikey .

2.) You seriously sacrificed additional subwoofer box volume so you could mount a factory amp that you are not even using? Wow, committed to a factory look even though you have two JL Audio amps and an MS-8 floating around back there

3.) I'm a little confused about the fiberglass material you used for the sub woofer floor. You mentioned some really cool open cell stuff that soaks up resin. But then you also mentioned regular weaved matt. Did you use both?

4.) I really like your subwoofer design. It came out fantastic. Question about the stacked ring construction though. Does each ring require it's own sheet of MDF? I see going through a lot of material.

5.) Please take a few snap shots of the completed center channel. I'd like to see how the bezel blends in with the car.

Thanks for taking the time to post your work.

Ge0

[Whiterabbit]

1) it is an aluminum project box. i wanted metal for durability and grounding. A raw circuit board in a non-EMI case in an automotive environment? That screams "NOISE!" to me! It had racks on the inside so I could slide in printed circuit material inside. The original intention was to make custom boards that the DSP were soldered to on standoffs. Then I realized that it was way overkill and totally unneeded. All I needed was perf board, cut to size so they fit into the box. The DSP PCA are secured to the perf board, and the perf board slides into the project box. They are held front to back by the case covers.

I got the box at Fry's, so I guess that makes it impossible to duplicate now

2) The factory amp is being used as a MOST converter. I could buy a MOST converter for $650, and get some more processing, or just use the factory amp. I chose to use the factory amp. It converts MOST to Analog, then I use the analog from there.

3) I'll try to make a post about this

4) Each ring requires its own MDF the size of the footprint used. I think the box is 22 inches wide, so I can get three layers out of a 2'x4' sheet of MDF. So, that box in total has 2 or 3 sheets of 2'x4' MDF in it. The construction is straight forward. The first layer is cut and sanded to perfection. Then the next layer is rough cut ti within 1/8", pined on with 2 pins, the cut with the flush cut or patternmaker bit. A screw driver is used to pry the pieces apart and needlenose pliers remove the pins. Same as any jig. If I don't need to take apart the stack, then I can glue and pin it right there, then buzz it smooth. Because of the contour chosen here, I elected to unpin the whole box and reconstruct it as needed. As I said before, the human hand can feel a gap of 0.001 pretty easy, and sandpaper and bodyfiller take care of the rest to get it as smooth as glass.

Bigger issue is the entire box is "end grain" of MDF which is a SERIOUS PAIN to fill for a painted finish! I've learned to use regular bodyfiller first, then followup with filler primer. First time I only used filler primer. I used alot of filler primer!

5) Car is ugly now. So be prepared for a far less impressive install Problem for the center channel is the grillecloth I used faded in the sun. Not good! If you have a recommendation for a fade-proof grille cloth, I am all ears. but I'll show you my car's arse, if you want to see it.




Let me grab more pics for a later post.

[Whiterabbit]

ugly pictures incoming

Here's the side hatch in the trunk


The long pigtail is plenty to have the laptop in any seat in the car. 2x USB and the cable for the MS-8 screen. Most of the time it is coiled up inside the panel. D-block is also seen, floating on some sheetmetal bolted to the unibody via machine screws.


Current trunk, taken today. The wiring has been cleaned up with fabric E-tape.



And center channel as she sits now. I like and use dash mats, they work when tuned in place. (same with the subwoofer, trunk panel has to be down). Dash mat aesthetics are the best China could come up with.


Unfortunately, sunbaking faded not only the black grillecloth, but also the Focal Be3 grillecloth. Only where the dash mat was open. Seen, obviously, in blue.




Sooooooooo ... the dash mat obviously lives in place to prevent this ugly fading from being seen.

(I wonder what the speaker cones and domes would look like if I DIDN'T have grille cloth covering!) =o

[Ge0]

ugly pictures incoming

Here's the side hatch in the trunk


The long pigtail is plenty to have the laptop in any seat in the car. 2x USB and the cable for the MS-8 screen. Most of the time it is coiled up inside the panel. D-block is also seen, floating on some sheetmetal bolted to the unibody via machine screws.


Current trunk, taken today. The wiring has been cleaned up with fabric E-tape.



And center channel as she sits now. I like and use dash mats, they work when tuned in place. (same with the subwoofer, trunk panel has to be down). Dash mat aesthetics are the best China could come up with.


Unfortunately, sunbaking faded not only the black grillecloth, but also the Focal Be3 grillecloth. Only where the dash mat was open. Seen, obviously, in blue.




Sooooooooo ... the dash mat obviously lives in place to prevent this ugly fading from being seen.

(I wonder what the speaker cones and domes would look like if I DIDN'T have grille cloth covering!) =o

I have high hopes for using the wireless adapter for my Helix DSP. No cables to tune or change settings. Woo Hoo!!!

As far as the sun fading. Now that there is strange. but in a sense kind of a pretty pattern. I'd be inclined to leave it

Ge0

[Whiterabbit]

You built your own miniDSP to save a few bucks. Damn that's dedication to taking the cheap way out . Have any more pictures of that? You fabricated your own aluminum box? I would have thought the cheap way out would be to order a cheap ABS plastic project box from Digikey .

Three more pictures of the ugly details. Ugly because rather than using a custom PCB sled to mount the DSP, I'm using perf board because it was good enough.

The project box is something like 2"x3"x5". Try to find a 4 in, 8 out signal processor on the market in that size, that can do all pass and FIR! Anyways, the box had shelves in it. Perfect for holding perf board or straight up PCB. Each board is mounted to perf strategically cut to fit exactly into the box. Additional cutouts are made to clear the cable connectors.

You can see the white wires which are cut to length, DB pin crimped on, and then soldered to the RCA connector. They sit inside the grounded enclosure, so they are "loose". Outside the box, they are twisted pair for noise rejection. The length is specific to allow the panel to be mounted and the boards slide into place. The remainder is internally organized after board installation.

The tricky part was USB soldering because of the size of the USB connector on the board. But thank God, it was still through hole, so soldering was easy enough and structure was in place not to tear components or traces off the board when stressed during install.

Overall, it works. The ugly perf board vanishes once the cap is put on, and the only thing left is an aluminum box with a proper bulkhead on it with the needed conectors, shown above.

[Whiterabbit]

3.) I'm a little confused about the fiberglass material you used for the sub woofer floor. You mentioned some really cool open cell stuff that soaks up resin. But then you also mentioned regular weaved matt. Did you use both?

So, let me start with a recap of what is used in 90% of cases that I see online for homemade fiberglass boxes. They are made out of 100% chopped mat cloth



This stuff is strong and unidirectional. But it has a couple problems that we deal with:

1. It doesn't conform to compound corners. so we cut it into strips or small squares so we can make complex shapes. Besides the extra work, that's messy!
2. It falls apart pretty much as soon as resin touches it. This leaves a mess of stray fibers everywhere. These often turn into little hypodermic needles waiting to stab you on the surface of your completed layup.
3. It is hard to impregnate, so we deal by overcompensating with resin. This results in the correct strength, but at the cost of excessive thickness and way too much weight!

Other than that, it works great and makes a strong box.

--------------------------------

So, the bottom of MY sub box is made up of three layers of material. Actually 4 since the bottom is upholstered in CCF as a cushion and to prevent rattling. But that's on top of the cured fiberglass panel.

So, the fiberglass panel consists of three different materials, layered. Each has a purpose.

Material 1. standard twill.

https://www.tapplastics.com/product/...ified_twill/84

This IMO is actually the best material to use for a glass box. It is easy to impregnate, takes just as much resin as needed, conforms to compound corners with ease, and has superior strength, due to having the proper ratio of glass to resin. But there are issues.

1. It pinholes like crazy.
2. Solve the pin holes by layering, and it makes finishing painful. Filling the weave takes FOREVER. worth it when you are working on a wood kayak with a piano finish. but it's not the work we want to put into something that's never seen.
3. To get the strength, we need tons of layers. That costs money, and takes time to layer up.

I use it for the exposed layers. Imagine that chopped mat cloth box above. Imagine laying over some twill cloth on top after the layups are done. The twill will stamp flat any chopped fibers sticking up and provide a fine surface. So I use it on the bottom of my box, the first layer I put down, to confirm to the trunk floor surface, and on the top layer, to give me a fine finished surface.



Material 2. Knytex X-mat

https://www.tapplastics.com/product/...nytex_x_mat/91

This stuff is great. It is only slightly thinner than woven roving, so it provides an immense amount of bulk in a single layer. stitched to it is a very very thin layer of chopped fiber. The chopped fiber adds non-directional stability. But they made it thin enough so the chopped fibers move when flexed, so the material conforms to compound corners. But the chopped fiber is stitched in, so it doesn't make a mess.

These are my "strength" layers! They eat resin like twill, conform to compound corners, keep the chopped mat in order, and give me the bulk of woven roving. All of that in just one or two layers so I save lots of money on having to layer up! I put these just under the surface. 1-2 layers is plenty even for a 15" subwoofer.


Material 3: Coremat (I think?)

https://www.tapplastics.com/product/...ics/coremat/93

I got it at Tap, so I think it's the same. all it does is drink up minimal resin and separate layers of proper glass fabric by 2mm while still bonding them together. Imagine the strength of thin cardboard vs the strength of foamcore board. The coremat is like the foamcore. I put one layer in my layup.

----------------


Overall, I had planned the following layup for my subbox:

twill
x-mat
x-mat
coremat
x-mat
coremat
x-mat
x-mat
twill

But after three layers, it was so clear that this layup was SO RIDICULOUSLY OVERKILL I abandoned that. I made my box:

twill
x-mat
x-mat
coremat
x-mat
twill

And it will survive the nuclear holocaust. The strength is ridiculous, and because there is no wasted resin in the panel, it's light. I save the weight for the 2" thick MDF walls

[Jscoyne2]

So, let me start with a recap of what is used in 90% of cases that I see online for homemade fiberglass boxes. They are made out of 100% chopped mat cloth



This stuff is strong and unidirectional. But it has a couple problems that we deal with:

1. It doesn't conform to compound corners. so we cut it into strips or small squares so we can make complex shapes. Besides the extra work, that's messy!
2. It falls apart pretty much as soon as resin touches it. This leaves a mess of stray fibers everywhere. These often turn into little hypodermic needles waiting to stab you on the surface of your completed layup.
3. It is hard to impregnate, so we deal by overcompensating with resin. This results in the correct strength, but at the cost of excessive thickness and way too much weight!

Other than that, it works great and makes a strong box.

--------------------------------

So, the bottom of MY sub box is made up of three layers of material. Actually 4 since the bottom is upholstered in CCF as a cushion and to prevent rattling. But that's on top of the cured fiberglass panel.

So, the fiberglass panel consists of three different materials, layered. Each has a purpose.

Material 1. standard twill.

https://www.tapplastics.com/product/...ified_twill/84

This IMO is actually the best material to use for a glass box. It is easy to impregnate, takes just as much resin as needed, conforms to compound corners with ease, and has superior strength, due to having the proper ratio of glass to resin. But there are issues.

1. It pinholes like crazy.
2. Solve the pin holes by layering, and it makes finishing painful. Filling the weave takes FOREVER. worth it when you are working on a wood kayak with a piano finish. but it's not the work we want to put into something that's never seen.
3. To get the strength, we need tons of layers. That costs money, and takes time to layer up.

I use it for the exposed layers. Imagine that chopped mat cloth box above. Imagine laying over some twill cloth on top after the layups are done. The twill will stamp flat any chopped fibers sticking up and provide a fine surface. So I use it on the bottom of my box, the first layer I put down, to confirm to the trunk floor surface, and on the top layer, to give me a fine finished surface.



Material 2. Knytex X-mat

https://www.tapplastics.com/product/...nytex_x_mat/91

This stuff is great. It is only slightly thinner than woven roving, so it provides an immense amount of bulk in a single layer. stitched to it is a very very thin layer of chopped fiber. The chopped fiber adds non-directional stability. But they made it thin enough so the chopped fibers move when flexed, so the material conforms to compound corners. But the chopped fiber is stitched in, so it doesn't make a mess.

These are my "strength" layers! They eat resin like twill, conform to compound corners, keep the chopped mat in order, and give me the bulk of woven roving. All of that in just one or two layers so I save lots of money on having to layer up! I put these just under the surface. 1-2 layers is plenty even for a 15" subwoofer.


Material 3: Coremat (I think?)

https://www.tapplastics.com/product/...ics/coremat/93

I got it at Tap, so I think it's the same. all it does is drink up minimal resin and separate layers of proper glass fabric by 2mm while still bonding them together. Imagine the strength of thin cardboard vs the strength of foamcore board. The coremat is like the foamcore. I put one layer in my layup.

----------------


Overall, I had planned the following layup for my subbox:

twill
x-mat
x-mat
coremat
x-mat
coremat
x-mat
x-mat
twill

But after three layers, it was so clear that this layup was SO RIDICULOUSLY OVERKILL I abandoned that. I made my box:

twill
x-mat
x-mat
coremat
x-mat
twill

And it will survive the nuclear holocaust. The strength is ridiculous, and because there is no wasted resin in the panel, it's light. I save the weight for the 2" thick MDF walls

neat thanks

[Ge0]

Three more pictures of the ugly details. Ugly because rather than using a custom PCB sled to mount the DSP, I'm using perf board because it was good enough.

The project box is something like 2"x3"x5". Try to find a 4 in, 8 out signal processor on the market in that size, that can do all pass and FIR! Anyways, the box had shelves in it. Perfect for holding perf board or straight up PCB. Each board is mounted to perf strategically cut to fit exactly into the box. Additional cutouts are made to clear the cable connectors.

You can see the white wires which are cut to length, DB pin crimped on, and then soldered to the RCA connector. They sit inside the grounded enclosure, so they are "loose". Outside the box, they are twisted pair for noise rejection. The length is specific to allow the panel to be mounted and the boards slide into place. The remainder is internally organized after board installation.

The tricky part was USB soldering because of the size of the USB connector on the board. But thank God, it was still through hole, so soldering was easy enough and structure was in place not to tear components or traces off the board when stressed during install.

Overall, it works. The ugly perf board vanishes once the cap is put on, and the only thing left is an aluminum box with a proper bulkhead on it with the needed conectors, shown above.

So your housing is an aluminum extrusion with end caps. I've designed many products this way.

Ge0

[Whiterabbit]

yeah. I got it at frys, but they are pretty ubiquitous.

https://www.zoro.com/box-enclosures-...si/i/G1125144/

[agm]

This install is fascinating and encouraging! I love how you straight up did it YOUR way and enjoyed the process and results! Great stuff!!!